Poisonous substances sometimes get released into the environment. these poisons can be more dangerous to animals at the top of the food chain explain why? i need the answer

Poisonous substances being released into the air can cause animals at the bottom of the food chain to have disease or death and decrease food supply to the upper members of the food chain. 

The answer to this will be from your lab notes/procedure. it would be best to ask another student who participated in the lab as we do not know what was done, what enzyme or if the temperature is celsius or fahrenheit. if i were to guess though i'd say the rate stopped due to enzyme denturing at high temperature